Plug



L A. SHARP Dec. 24, 1935.

ATTO R N EYS' PLUG Filed Aug. 25, 1933 Patented Dec. 24, 1935 g PLUG L Alan Sharp, Bellevue, Pa

Electric Products Corporation,

., assignor to National New York, N. Y.,

a corporation of Delaware Application August 25, 1933, Serial No. 686,719

8 Claims. (Cl.

This invention relates to improvements in telep phone plugs of the type i and what I now anying specification and claims and shown in the drawing which shows by way of illustration preferred embodiment and the principle thereof consider to be the best mode in ough a cord to a plug and such plug is adapted which I have contemplated of applying that printo be plugged into a jack to connect the phones ciple. Other embodiments of the invention emwith a telephone circuit. ploying the same or equivalent principle maybe when telephones are used in certain places, for example in gun turrets or in other. hazardous locations, occasion sometimes arises where the user A further object of the present invention resides in the provision of'a plug with improved conducmeans and improved strain relief means associated therewith.

Another object of the provided with strain relief means to prevent daml conductors of the cord which will provide a main- A further object of the present invention resides in the provision of a plug with terminal means thereon which will permit the elimination of terminal elements upon the ends of the conductors.

in section cable being shown in stantially on line the direction of the arrow partly in section and partly in side elevation;

which one of the conductors ing screw terminal preferably of brass, which an insulating sleeve ll.

of the sleeve I2 is provided erture I 3 adapted to receive insulating material ll. lar is received between 01 the rod l0 and the end of the insulating sleeve threaded end of the rod holds all of the above assembly. The conductor erally designated l1, such Within which are a pair used and structural changes made as desired by those skilled the present invention and within the spirit of the in the art without departing from ppended claims.

In the drawing:

Figure 1 shows an assembled view of plug and rotecting sheath, the sheath alone being shown and the plug parts and cooperating side elevation;

Fig. 2 is an enlarged sectional view taken su 22 of Fig. l and looking in The cord is shown Fig. 3 is a sectional view taken substantially 11 line 3-3 of Fig. 2 and looking in the direction of the arrows and shows the tying of the filler cords to provide a strain relief connection to the cord; and

Fig. 4 is a sectional view taken substantially n line l4 of Fig. 2 andshows the manner in is fastened to a bindelement on the plug. Fig. 5 shows another embodiment of the inention.

In moredetail and referring particularly to Fig. the plug comprises a central rod I 0 which is rod is surrounded by Surrounding the sleeve I is a. metallic sleeve It. An extended portion with an annular apa shouldered p'ortion I5 I. A ball or contact tip I 6 is screwed on the or conducting core Ill and mentioned parts in a tight cable or cord is gencord comprising an 18 preferably of rubber of individually insulated and also including filler uter jacketed portion onductors I9 and 20 A furt r obj c of e present invention resides cords 2|. Preferably in practice the conductors in the provision of a plug with a resilient jacket I9 and 20 are closely wound around the filler of rubber or like material. cords 2| This provides a conductor with maxi- Further and other objects of the present invention will be hereinafter set forth in the accommum flexibility so that when the filler cords are used for strain relief the pulling strains will be securing the cord in the ing the conductors nection in the small space pro directly exerted upon the filler cords instead of upon the conductors i9 and 20.

In assembling the cord to the plug the end portion of the outer jacket 18 is cut away, leavl9 and 20 and the filler cords 2| projecting. One of the conductors, viz. I9 is then laterally through an opening 22 in the sleeve l2 (see Fig. 4) and the wire of the conductor is then fastened under the head of the binding screw 23, which binding screw is threaded into a rear portion of the sleeve l2 on the outside thereof. The other conductor 20 is passedthrough a hole 24 in the bottom of the cup 25. The cup 25 is then pressed over the end of the rod l0 between the rod and the flanged insulating collar ll, thus securing the cup to the conducting core l0 and thus pressing the spreaded end 26 of conductor 20 against the inner end of the rod or core l0 and securing it thereto. The filler cords 2| are then passed through other holes 21 in the rear portion of the sleeve l2 (see Fig. 3) and are wound around a groove 28 in such sleeve l2. They are finally tied as shown in Fig. 3.

As shown, it will be noted that slack is left in the conductors l9 and 20 when the filler cords 2| are tied. Such slack is shown adjacent the end of the lead line for reference numeral 20 on Fig. 2. A resilient sheath 29, preferably made of yielding rubber is stretched over the rear end of the assembled plug and cable 11. This sheath has an inwardly extending shouldered portion 30 which looks behind a shoulder 3! on the sleeve l2 and the sheath also cooperates with another shoulder 32 of the sleeve l2. Preferably the end of the sheath is provided with beaded ends 33 (see Fig. 1) which are initially slightly smaller than the external diameter of the cord l1 so as to stretch over the cord and tightly grip it when the sheath is in position over the cord. The sheath provides for a wate -tight assembly and also protects the conductor connections, the filler cord connections and the rear end of the plug from mechanical injury.

The arrangement of the shoulders 3| and 32 cooperating with shouldered portions-of the flexible sheath allows the plug to be withdrawn and inserted by means of pulling and pushing on the from pulling out or pushing back into the sheath.

In a plug of this type it will be understood that the parts be relatively small in size. i. e. particularly such'that the cord engaging or body portion be as small as conveniently possible. At the same time the arrangement for making the necessary electrical connections and for mechanically plug should be readily accessible and should be such as to provide a firm and secure electrical and mechanical convided.

with the construction shown the binding screw terminal 23 is accessible on the outside of the rear portion of the sleeve and accessibility is provided for tying the filler cords before the resilient sheath is placed in position. The resilient sheath may be stretched over the rear end of the plug and when in position not only covers the conductor connection at terminal 23 and the tied filler cords, but yieldingly grips the binding screw and the filler cord knots.

In Fig. .5 I have shown my improved plug construction with a protective sheath 29a of slightly different configuration. The plug per se is substantially the same as that previously described but the protective rubber sheath 29a is substanthe shelf 36.

tion with the conductors of comprising a conducting core the interior plug assembly tially cylindrical in outer configurationin place of being tapering as in the previously described embodiments and such sheath has a lower shoulder 35 adapted'to act as an abutment and cushion the plug when the same to its vertical position through the aperture in .In falling the shoulder 35 resiliently abuts the top of the key shelf of a telephone switchboard and thus cushion the arrest of the plug by the key shelf. 10

It will be appreciated that silencing material customarily applied to the key shelf may be eliminated, for the plug body or. sheath is made of yielding or self-silent material as here shown.

The improved plug construction is us wall switch boards of the usual type with plugsand cords pendant from the bottom which cords plugged into jacks at the bottom of the switch board. With such switch is considerable abuse both to, the 20 plugs and to the wall switches between the plugs when the plugs are withdrawn from the jack and dropped to their natural pendant position. Under such conditions the resilient sheath prevents damage to the wall and strain is relieved 25 from the connections in the manner previously explained.

What I claim is:

1. A plug for use with a jack and for connecan electrical cord, 30

member, a contact tip upon the forward end of said member,

a cup pressed over the rear end of said core member and provided with a hole through which an electrical conductor may be passed, said cup as holding the conductor tightly against the rearward end of,the aforesaid core, a metal sleeve surrounding the core and insulated therefrom and from the contact tip, means providing a conductor connection to said sleeve, and a sheath of 40 resilient material tightly fitted over the rear end of the plug and alsoover a portion of the entering electrical cord.

2. The invention set forth in claim- 1 in which the means for securing a conductor to the sleeve comprises a. binding screw cooperating with the sleeve and in which the sleeve is provided with a hole through which a conductor may be passed to extend to the aforesaid binding screw.

3. A plug for use with a jack and for connection to the conductors of an electrical cord,-comprising a contact tip and sleeve insulated from each other with the tip carried upon a core which extends through the sleeve and which is also insulated therefrom, means providing conductor connections to the core and to the sleeve, said sleeve having a grooved portion extending peripherally therearound and disposed beyond the point of conductor connection the filler cords of an electrical cord may be laid, so and secured and a sheath of resilient. material fitted over the rear end of the plug and over the aforesaidgroove and also embracing a portion of the entering electrical cord.

4. A plug for use with a jack and for conneco5 cord, comprising a contact tip'carried upon a core, a sleeve around the core and insulated therefrom said sleeve having a hollow which the conductors of an 7( electrical cord may be extended, and whereby one conductor may be connected to the rear of the core, said. rear .portion of said sleeve carrying v a binding screw and having a pair of peripheral outer grooves, said sleeve having ap rtures there- 7.

is allowed to fall 5 eful with 15 the binding screw upon the through to each of the said grooveaone groove providing space for a conductor which passes through one of the apertures and extends to sleeve, the other groove receiving tied filler cords which also pass the rear portion of the plug and also embraces I through sleeve apertures.

5. The invention set forth in claim 4 in which the filler cord groove is disposed intermediate the point of conductor fastening and the rear end of the plug where the cord enters the plug whereby slack may be maintained in the conductors at the point of fastening to the plug elements.

6. The invention set forth in claim 4 in which a resilient sheath is provided which tightly grips a portion of the plug and also embraces a portion of the entering. cord.

7. A plug for use with a jack and adapted for connection with the conductors of an electrical cord, said plug comprising a contact tip, a contact sleeve and a conducting core secured to the tip with an insulating sleeve between it and the contact sleeve, said contact sleeve having an integral rear hollowed out portion into which the rear of the core extends, a cup-shaped member upon the rear end 01 the core providing a securing means for one conductor of the electrical cord, 9. binding screw on the outside of the integral rear portion with a groove in said integral rear portion extending to an aperture through said portion into the hollow interior and providing a passage for another conductor which emerges Irom the hollow interior, said portion also being provided with another groove for receiving and securing the filler cords of the core, which filler cords also pass through apertures in said rear portion, and a sheath of resilient material enclosing and gripping the rear portion of the plug and also enclosing a portion of the cord entering said plug.

8. A plug for use with a jack comprising the usual contact tip and sleeve elements insulated from each other with the sleeve at its rear end provided with an extension having a recess portion therein into which filler cords of an electrical cord may extend, said extension having 20 apertures therethrough leading to a groove extending annularly onthe outside of the extension to provide for passing the filler cords from within the sleeve into said groove, said groove providing for accessible tying of the filler cords. 25

L ALAN SHARP. 

